Exclude sub-meters from category subtotals in Estimates/Reports/internal API

Water Softener is configured as a submeter (parent_meter_id) of Main Hotel
Water, but estimates.js, reports.js, and internal.js's cost + estimate
routes summed every active meter flatly regardless of parent/child, double-
counting the softener's consumption on top of the main meter's own reading.

Sub-meter rows are still shown individually (useful for diagnostics), just
excluded from the category subtotal/total sums, with a 'submeter' badge on
the row explaining why. Fixes the water figures on Estimates, Reports, and
downstream consumers of internal.js (Directors report, Weekly Actuals).

backend/src/routes/estimates.js

@@ -7,7 +7,7 @@ const VALID_WINDOWS = [7, 14, 30]
 async function estimateForMeter(meter, periodStart, periodEnd, windowDays) {
   const estimate = await getMeterEstimateForPeriod(meter.id, periodStart, periodEnd, windowDays)
   return {
-    meter_id: meter.id, meter_name: meter.name,
+    meter_id: meter.id, meter_name: meter.name, parent_meter_id: meter.parent_meter_id,
     category_id: meter.category_id, category_name: meter.category_name, unit_label: meter.unit_label,
     ...estimate,
   }
@@ -29,7 +29,7 @@ export async function estimateRoutes(app) {
     if (category_id) { params.push(category_id); conditions.push(`m.category_id = $${params.length}`) }
     params.push(globalDefault)
     const { rows: meters } = await pool.query(
-      `SELECT m.id, m.name, m.category_id, c.name AS category_name, c.unit_label,
+      `SELECT m.id, m.name, m.category_id, m.parent_meter_id, c.name AS category_name, c.unit_label,
               COALESCE(c.estimate_trailing_days, $${params.length}) AS trailing_days
        FROM meters m JOIN meter_categories c ON c.id = m.category_id
        WHERE ${conditions.join(' AND ')}`,
@@ -42,7 +42,12 @@ export async function estimateRoutes(app) {
       results.push(await estimateForMeter(m, start, end, windowDays))
     }
 
-    const totals = results.reduce((acc, r) => ({
+    // Sub-meters (parent_meter_id set) measure a subset of their parent's own
+    // reading — e.g. the water softener sits inline on the main supply — so
+    // their consumption/cost is already counted via the parent and must be
+    // excluded here to avoid double-counting. Still returned as their own row
+    // above so the projection is visible per-device.
+    const totals = results.filter(r => !r.parent_meter_id).reduce((acc, r) => ({
       total_pence: acc.total_pence + r.total_pence,
       usage_cost_pence: acc.usage_cost_pence + r.usage_cost_pence,
       standing_cost_pence: acc.standing_cost_pence + r.standing_cost_pence,

backend/src/routes/internal.js

@@ -38,7 +38,7 @@ async function categoryCostBreakdown(start, end) {
   }
 
   for (const cat of categories) {
-    const { rows: meters } = await pool.query('SELECT id, name FROM meters WHERE category_id = $1 AND active = TRUE', [cat.id])
+    const { rows: meters } = await pool.query('SELECT id, name, parent_meter_id FROM meters WHERE category_id = $1 AND active = TRUE', [cat.id])
     if (meters.length === 0) continue // no meters yet (e.g. Water/Oil seeded but unused) — nothing to report
 
     const catTotals = {
@@ -48,18 +48,26 @@ async function categoryCostBreakdown(start, end) {
 
     for (const m of meters) {
       const cost = await getMeterCostForPeriod(m.id, start, end)
-      if (cost.has_data) catTotals.consumption += cost.consumption
+
-      catTotals.usage_cost_pence += cost.usage_cost_pence
+      // Sub-meters (parent_meter_id set) measure a subset of their parent's
-      catTotals.standing_cost_pence += cost.standing_cost_pence
+      // own reading (e.g. the water softener sits inline on the main
-      catTotals.ccl_cost_pence += cost.ccl_cost_pence
+      // supply) — already counted via the parent, so excluded from the
-      catTotals.rab_levy_cost_pence += cost.rab_levy_cost_pence
+      // category totals to avoid double-counting. Still returned as its own
-      catTotals.metering_cost_pence += cost.metering_cost_pence
+      // row below for callers that want meter-level detail.
-      catTotals.other_charges_cost_pence += cost.other_charges_cost_pence
+      if (!m.parent_meter_id) {
-      catTotals.vat_pence += cost.vat_pence
+        if (cost.has_data) catTotals.consumption += cost.consumption
-      catTotals.total_pence += cost.total_pence
+        catTotals.usage_cost_pence += cost.usage_cost_pence
+        catTotals.standing_cost_pence += cost.standing_cost_pence
+        catTotals.ccl_cost_pence += cost.ccl_cost_pence
+        catTotals.rab_levy_cost_pence += cost.rab_levy_cost_pence
+        catTotals.metering_cost_pence += cost.metering_cost_pence
+        catTotals.other_charges_cost_pence += cost.other_charges_cost_pence
+        catTotals.vat_pence += cost.vat_pence
+        catTotals.total_pence += cost.total_pence
+      }
 
       meterRows.push({
-        meter_id: m.id, meter_name: m.name,
+        meter_id: m.id, meter_name: m.name, parent_meter_id: m.parent_meter_id,
         category_id: cat.id, category: cat.key, category_name: cat.name, unit_label: cat.unit_label,
         consumption: cost.consumption, has_data: cost.has_data,
         status: cost.status, as_of_date: cost.as_of_date,
@@ -184,18 +192,26 @@ export async function internalRoutes(app) {
 
     for (const cat of categories) {
       const windowDays = cat.estimate_trailing_days || globalDefault
-      const { rows: meters } = await pool.query('SELECT id, name FROM meters WHERE category_id = $1 AND active = TRUE', [cat.id])
+      const { rows: meters } = await pool.query('SELECT id, name, parent_meter_id FROM meters WHERE category_id = $1 AND active = TRUE', [cat.id])
       let catConsumption = 0
       let catTotalPence = 0
 
       for (const m of meters) {
         const estimate = await getMeterEstimateForPeriod(m.id, start, end, windowDays)
         remainingDays = estimate.remaining_days
-        if (estimate.projected_consumption != null) catConsumption += estimate.projected_consumption
+
-        catTotalPence += estimate.total_pence
+        // Sub-meters (parent_meter_id set) project a subset of their parent's
+        // own consumption (e.g. the water softener sits inline on the main
+        // supply) — already counted via the parent, so excluded from the
+        // category total to avoid double-counting. Still returned as its own
+        // row below for callers that want meter-level detail.
+        if (!m.parent_meter_id) {
+          if (estimate.projected_consumption != null) catConsumption += estimate.projected_consumption
+          catTotalPence += estimate.total_pence
+        }
 
         meterRows.push({
-          meter_id: m.id, meter_name: m.name,
+          meter_id: m.id, meter_name: m.name, parent_meter_id: m.parent_meter_id,
           category_id: cat.id, category: cat.key, category_name: cat.name, unit_label: cat.unit_label,
           trailing_window_days: estimate.trailing_window_days, daily_rate: estimate.daily_rate,
           actual_to_date: estimate.actual_to_date, remaining_days: estimate.remaining_days,

backend/src/routes/reports.js

@@ -16,7 +16,7 @@ export async function reportRoutes(app) {
     let where = ''
     if (category_id) { params.push(category_id); where = 'WHERE m.category_id = $1' }
     const { rows: meters } = await pool.query(
-      `SELECT m.id, m.name, m.category_id, c.name AS category_name, c.unit_label
+      `SELECT m.id, m.name, m.category_id, m.parent_meter_id, c.name AS category_name, c.unit_label
        FROM meters m JOIN meter_categories c ON c.id = m.category_id
        ${where} ORDER BY c.sort_order, m.name`,
       params
@@ -26,13 +26,18 @@ export async function reportRoutes(app) {
     for (const m of meters) {
       const cost = await getMeterCostForPeriod(m.id, start, end)
       results.push({
-        meter_id: m.id, meter_name: m.name,
+        meter_id: m.id, meter_name: m.name, parent_meter_id: m.parent_meter_id,
         category_id: m.category_id, category_name: m.category_name, unit_label: m.unit_label,
         ...cost,
       })
     }
 
-    const totals = results.reduce((acc, r) => ({
+    // Sub-meters (parent_meter_id set) measure a subset of their parent's own
+    // reading (e.g. the water softener sits inline on the main supply), so
+    // their consumption/cost is already counted via the parent — excluded
+    // here to avoid double-counting; still shown as their own row above, and
+    // separately compared against their parent in the rollup report below.
+    const totals = results.filter(r => !r.parent_meter_id).reduce((acc, r) => ({
       consumption: acc.consumption + (r.consumption || 0),
       usage_cost_pence: acc.usage_cost_pence + r.usage_cost_pence,
       standing_cost_pence: acc.standing_cost_pence + r.standing_cost_pence,

frontend/src/pages/Estimates.tsx

@@ -6,8 +6,12 @@ import * as api from '../api'
 
 const WINDOW_OPTIONS = [7, 14, 30]
 
+// Sub-meters (parent_meter_id set) project a subset of their parent's own
+// consumption (e.g. the water softener sits inline on the main supply) — their
+// row is still shown for visibility, but excluding them here avoids the
+// subtotal double-counting water/energy that's already in the parent's figure.
 function sumEstimateCosts(rows: EstimateRow[]) {
-  return rows.reduce((acc, r) => ({
+  return rows.filter(r => !r.parent_meter_id).reduce((acc, r) => ({
     projected_consumption: acc.projected_consumption + (r.projected_consumption || 0),
     total_pence: acc.total_pence + r.total_pence,
   }), { projected_consumption: 0, total_pence: 0 })
@@ -104,7 +108,14 @@ export default function Estimates() {
                       <Fragment key={group.category_id}>
                         {group.rows.map(m => (
                           <tr key={m.meter_id}>
-                            <td>{m.meter_name}</td>
+                            <td>
+                              {m.meter_name}
+                              {m.parent_meter_id && (
+                                <span className="badge" style={{ marginLeft: 6 }} title="Sub-meter — reads a subset of its parent meter, excluded from the subtotal below to avoid double-counting">
+                                  submeter
+                                </span>
+                              )}
+                            </td>
                             <td className="num">{m.trailing_window_days}d</td>
                             <td className="num">{m.daily_rate != null ? formatUnits(m.daily_rate, `${m.unit_label}/day`) : '—'}</td>
                             <td className="num">{formatUnits(m.actual_to_date, m.unit_label)}</td>

frontend/src/pages/Reports.tsx

@@ -8,8 +8,12 @@ function extrasFor(m: { ccl_cost_pence: number; rab_levy_cost_pence: number; met
   return m.ccl_cost_pence + m.rab_levy_cost_pence + m.metering_cost_pence + m.other_charges_cost_pence
 }
 
+// Sub-meters (parent_meter_id set) read a subset of their parent's own
+// reading (e.g. the water softener sits inline on the main supply) — their
+// row is still shown for visibility, but excluding them here avoids the
+// subtotal double-counting water/energy that's already in the parent's figure.
 function sumMeterCosts(rows: MeterCostRow[]) {
-  return rows.reduce((acc, r) => ({
+  return rows.filter(r => !r.parent_meter_id).reduce((acc, r) => ({
     consumption: acc.consumption + (r.consumption || 0),
     usage_cost_pence: acc.usage_cost_pence + r.usage_cost_pence,
     standing_cost_pence: acc.standing_cost_pence + r.standing_cost_pence,
@@ -97,6 +101,11 @@ export default function Reports() {
                           <tr key={m.meter_id}>
                             <td>
                               {m.meter_name}
+                              {m.parent_meter_id && (
+                                <span className="badge" style={{ marginLeft: 6 }} title="Sub-meter — reads a subset of its parent meter, excluded from the subtotal below to avoid double-counting">
+                                  submeter
+                                </span>
+                              )}
                               {m.rate_changed_mid_period && (
                                 <span className="badge badge-tou" style={{ marginLeft: 6 }} title={m.segments.map(s => `${s.tariff_name}: ${s.seg_start} – ${s.seg_end}`).join(', ')}>
                                   rate changed

frontend/src/types.ts

@@ -180,6 +180,7 @@ export type ConsumptionBasis = 'no_data' | 'partial' | 'complete' | 'distributed
 export interface MeterCostRow extends CostBreakdown {
   meter_id: number
   meter_name: string
+  parent_meter_id: number | null
   category_id: number
   category_name: string
   unit_label: string
@@ -260,6 +261,7 @@ export interface RollupReport {
 export interface EstimateRow extends CostBreakdown {
   meter_id: number
   meter_name: string
+  parent_meter_id: number | null
   category_id: number
   category_name: string
   unit_label: string